This application claims the priority of German patent application 196 47 300.4.
The invention relates to an arrangement for vertically changeably supporting an individual wheel carrier disposed by way of control arms or of an axle beam on the body of a motor vehicle, having an actuator which is fastened on the vehicle body, is constructed as a hydraulic motor with at least one pressure space, and whose swivellable actuating shaft acts by way of a linkage, which contains at least one lever arm, upon the wheel carrier, its control arms or the axle beam.
Such an arrangement is known from the "Manual for Automotive Engineering", Page 729, by Buschmann/Koessler, Wilhelm Heyne Publishers, Munchen, of the year 1976. The arrangement shown there actuates by means of an actuator an approximately vertically aligned lever arm which, by way of a torsion bar parallel to the longitudinal axis of the vehicle, acts upon a second, horizontally situated lever arm which is parallel to the axle on a semiaxle of the vehicle. Between the axle beam of the semiaxle of the vehicle and the lever arm, a bar is installed for the power transmission. The torsion bar is rotatably disposed on the vehicle body in at least one swivel joint. The arrangement requires several suspension points on the vehicle body and a lot of space for the high-expenditure linkage. In addition, it has a stiffness which cannot be controlled.
The invention is based on the need for an arrangement for the vertically changeable support of an individual wheel carrier disposed by way of control arms or of an axle beam on the vehicle body of a motor vehicle which, as an active chassis control, can absorb vibration excitations generated by the road. While it requires little space and a small number of parts, the arrangement must also be secure with respect to an overloading, and should be maintenance-free or at least require low maintenance.
This and other needs have been met according to the present invention by providing an arrangement for vertically changeably supporting a wheel carrier relative to a motor vehicle body, comprising: a hydraulic motor coupled to the vehicle body, said hydraulic motor including at least one loaded hydraulic pressure space which is communicated with at least one of (a) a less- or non-loaded pressure space or a return flow via at least one return valve, and (b) a hydraulic accumulator; and at least one lever arm operatively coupled to each of said hydraulic motor and said wheel carrier such that said lever arm is rotatable relative to said hydraulic motor.
This and other needs have been met according to the present invention by providing a method of vertically changeably supporting a wheel carrier relative to a motor vehicle body, comprising: coupling a hydraulic motor with at least one loaded hydraulic pressure space to the vehicle body; communicating said loaded hydraulic pressure space with at least one of (a) a less- or non-loaded pressure space or a return flow via at least one return valve, and (b) a hydraulic accumulator; and operatively coupling at least one lever arm to each of said hydraulic motor and said wheel carrier such that said lever arm is rotatable relative to said hydraulic motor.
The lever arm, upon which the hydraulic actuator acts directly, is designed as a mechanical spring. Also, at least one loaded pressure space of the actuator is hydraulically connected by way of at least one return valve with a less loaded or non-loaded pressure space or a return flow. By way of the return valve, an unacceptable pressure rise in the loaded pressure space, for example, as the result of a compression of a wheel because of an uneven point in the road, is reduced immediately. As an alternative or in addition to the return valve, the loaded pressure space may also be connected to a hydraulic accumulator which reduces the stiffness of the hydraulic actuator.
The arrangement, which, among other things, can be used as a level control system, supports the corresponding wheel--without the intermediate connection of the regular suspension--elastically by means of mechanical and optionally hydraulic devices. In addition, an overloading of the arrangement which impairs the driving comfort or the operation is prevented by at least one return valve.
The hydraulic motor may, for example, be a swing piston motor with at least one loaded pressure space. A rotating cylinder or the like is also contemplated.
For transmitting the swivel motion of the lever arm to the wheel carrier or its control arms or to the axle beam, a bar can be arranged between the free end of the lever arm and a corresponding linking point on the control arm or axle beam. The bar compensates by means of tilting movements, among others, the displacement of its two linking points during the compression and rebounding of the corresponding wheel. Naturally, instead of the bar, a linking can also be used, among others, which has at least one slide joint.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.